共查询到18条相似文献,搜索用时 140 毫秒
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利用超声“脉冲回波重合法”技术,测定了立方晶体镱镓石榴石(GGG)各对称方向的超声波声速,及它们在流体静压力和单轴应力条件下,随压力的变化,计算了GGG的二阶和三阶弹性常数。它们分别是:c11=3.04,c12=1.31,c44=0.94和c111=-17.97,c112=-12.86,c123=-1.06,c144=-2.11,c166=-3.29,c456=-0.94,单位是1011 N/m2。根据这些数据,我们还计算了GGG晶体的德拜温度以及沿它的[001]→[111]→[110]→[100]传播的三个声学波分支(一个纵波,两个横波)的Gruneisen参数γ(p,N)的分布。 相似文献
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利用Mao-Bell型金刚石对顶砧装置(DAC),使用4∶1的甲醇-乙醇混合液作传压介质,研究了层状铁电固溶体Ba3Bi3Ti4NbO18的在位高压拉曼光谱和压致结构相变(0~8.87 GPa)。观测到了Ba3Bi3Ti4NbO18的一个典型的压致结构相变。发现了赝钙钛矿结构A4B5O16的A位和B位联合置换对Ba3Bi3Ti4NbO18的拉曼振动模式及压致相变点的调制作用。并使用内模方法对Ba3Bi3Ti4NbO18的内模进行了指认。通过对加压下的拉曼光谱的分析,得到了压力作用下样品中BO6八面体的结构畸变的演化方向。 相似文献
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在3~20 GPa压力范围内,测量了含氧量较低的YBa2Cu3O7-δ(δ=0.46)单晶压力增强效应(dTc/dp=4.9KGPa-1);YBa2Cu3O7(Tc0=90 K)单晶在压力下临界电流密度随压力变化;外磁场H=30 kOe时,Tc与磁场、压力关系;压力达16.5 GPa下,Bi2Sr2CaCu2Ox单晶Tc(p)关系(dTc/dp=-0.4 KGPa-1)。发现Y系高温超导体的温度压力导数dTc/dp与Tc0中间呈dTc/dp=b-mTc0线性关系(b、m为常数)。结合压力下Y系超导体结构相变和含氧量对Tc影响,分析这类超导体Tc有很强的正压力效应的原因。把实验结果同几种超导电性微观理论模型进行了分析和比较。 相似文献
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高压下材料弹性声速的一种经验表达式 总被引:1,自引:1,他引:0
将铝、铁、铜等七种材料弹性声速的实测数据进行分析处理发现,其弹性声速随压力的变化均可以用一下关系:ln c=A0+A1ln p+A2ln2p,很好的拟合。拟合结果与实测值的相对误差小于5%。 相似文献
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本文研究了Fe40Ni40P12B8非晶合金冲击波加载下的晶化行为,冲击波由二级轻气炮发射的告诉弹丸撞击靶产生。实验结果表明:Fe40Ni40P12B8非晶合金在冲击波加载下,晶化可在加载时间(微秒量级)内发生;晶化的阈值压力在30~50 GPa之间,相应的冲击温度约为510~800 K,晶化析出相与冲击压力有关,低压下析出相是面心立方γ-(Fe, Ni)固溶体和Fe3(P0.37B0.63)化合物,高压下(大于60 GPa)析出相除了面心立方γ-(Fe, Ni)固溶体和Fe3(P0.37B0.63)化合物之外,还包括(Fe, Ni)3P化合物。 相似文献
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用光分析技术,测量了在一维应变冲击条件下,无氧铜的高压下声速,压力范围为125~170 GPa。将上述结果与Broberg、Morris等和Aльгшуер等过去发表的数据结合在一起,对0~170 GPa整个压力区间的声速数据做了综合分析,给出了声速随压力的变化规律。实验结果发现,无氧铜在156~159 GPa之间开始发生冲击熔化,到170 GPa左右,完全进入液相区;对于处于0~156 GPa固体无氧铜的弹性声速cl可用ln cl=1.565 888-2.645 488×10-2ln p+2.710 681×10-2ln2p拟合公式描述(p的单位为GPa,cl的单位为km/s),拟合值与实验值的相对误差小于1.3%。 相似文献
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首次采用高压高温方法合成了Sr2SiO4:Er3+Bi3+和SrSiO3:Er3+Bi3+发光材料,研究了合成压力、合成温度对发光特性的影响。与常压合成产物相比较,发光谱发生了红移;谱线半宽度显著增大;发光强度和量子发光效率下降。X射线衍射分析得出,SrSiO3:Er3+Bi3+发生了结构相变,Sr2SiO4:Er3+Bi3+结构未变但晶格参数发生了变化,且主衍射峰强度发生了反转。分析表明,发光特性的变化是压致晶场、库仑及自旋-轨道相互作用的变化引起的。 相似文献
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Vladimir Skarka Marina M. Lekić Aleksander G. Kovačević Boban Zarkov Nebojša Ž. Romčević 《Optical and Quantum Electronics》2018,50(1):37
We present here the experimental, theoretical, and numerical investigations of Kerr solitons generated by self-organization in black and yellow high quality bismuth germanium oxide (Bi12GeO20) single crystals. A picosecond laser beam of increasing power induces competing cubic and quintic nonlinearities. The numerical evolution of two-dimensional complex cubic-quintic nonlinear Schrödinger equation with measured values of nonlinearities shows the compensation of diffraction by competing cubic and quintic nonlinearities of opposite sign, i.e., the self-generation and stable propagation of solitons. Experiments as well as numerical simulations show higher nonlinearity in the black Bi12GeO20 than in the more transparent yellow one. 相似文献
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Y.H. Ja 《Optics Communications》1982,42(6):377-380
Based on a classical two-exposure holographic technique, real-time image subtraction is obtained in four-wave mixing of a reflection hologram type with highly sensitive photorefractive Bi12GeO20 crystals. This method takes advantage of the relatively slow response and erasure times of holographic recording in Bi12GeO20 crystals. 相似文献
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A. T. Efremidis N. C. Deliolanis C. Manolikas E. D. Vanidhis 《Applied physics. B, Lasers and optics》2009,95(3):467-473
The photorefractive crystals of the sillenite family (Bi12SiO20 or BSO, Bi12GeO20 or BGO, and Bi12TiO20 or BTO) that belong to the cubic 23 point group are optically active, and exhibit the piezoelectric, elasto-optic, electro-optic
and electrogyration effect. In this paper we measure the dispersion of the electro-optic coefficient for all the crystals
of the sillenite family in the visible spectral range (500–800 nm). For this we measure by ellipsometry the polarization properties
of a beam transmitted in the transverse configuration under the action of an externally applied field. The experimental data
are fitted with an analytical expression of the beam polarization to find the electro-optic coefficient. The results show
a normal dispersion of the electro-optic coefficient in all three sillenite crystals, similarly to other electro-optic crystals. 相似文献
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From Raman data and a group-theoretical analysis, we deduce that in Bi12GeO20 and Bi12SiO20 there are four weakly bound oxygen atoms and a tightly bound unit MO4, where M = Ge or Si. Some normal modes of the tightly bound units are identified in Raman and in infrared reflection data. The kinds of interatomic binding forces in these crystals are determined. The results are compared with structure data determined by X-ray scattering. 相似文献
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In this paper we report on the dispersion of the electrogyration of the sillenite crystals Bi12SiO20, Bi12GeO20, and Bi12TiO20 over the visible spectrum. We measure the electrogyration coefficient from the rotation of the polarization plane of the transmitted beam due to the externally applied electric field. Both light transmission and electric field direction are parallel to the [111] crystallographic direction in which the influence of the electrooptic effect is diminished. In all cases the electrogyratory coefficient is found to be between 0.5–3.75×10-13 m/V and has the same dispersion pattern like optical activity and refractive index. PACS 78.20.Ek; 78.20.Jq; 42.70.Nq 相似文献
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O. M. Bordun I. I. Kukharskii T. M. Yaremchuk S. I. Gaidai 《Journal of Applied Spectroscopy》2004,71(3):382-386
The dispersion of light in Bi4Ge3O12 and Bi12GeO20 single crystals and thin Bi2O3 films with a monoclinic structure was investigated in the visible spectral region. The parameters of a single-oscillator approximation have been found. It is established that in Bi4Ge3O12 crystals the absorption band caused by the O2p–Bi6p transitions makes the main contribution to the dispersion curve in the visible region, whereas in Bi12GeO20 crystals this is made by transitions from the hybrid O2p–Bi6p states to the conduction band. The dispersion energy, the degree of the ionicity of binding, and the coordination number of the first coordination sphere of the Bi3+ cation have been determined. 相似文献
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Laevorotatory crystals of isomorphous Bi12SiO20 and Bi12GeO20 are shown, by use of the anomalous X-ray scattering component in the structure amplitudes, to have identical chirality (handedness of atomic arrangement) in contrast with the case of NaC103 and NaBrO3, in which crystals of the same chirality rotate plane polarized light in opposite senses. 相似文献